Pump and process of setting the piston thereof



March 11V, 1941 l; D. sTRr-:BY

PUMP AND PROCESS OF SETTING THE PISTON THEREOF Filed March 26. 1958 3 Sheets-Sheet l March 11, 1941..

R. D. STREBY PUMP AND PRDCESS OF SETTING vTHE PISTON THEREOF 3 'Sheets-Sheet 2 Filed Hgmh 26. 1938 E m F. w

` March 11, 1941.

R D. sTREBY 2,234,936

PUMP AND PRUCESS V0F SETTING THE PISTON THEREOF Filed March 26, 1938 3 Sheets-Sheet 5 PUMP SPEED /N RJQ. M. /A/VENTQE: 0 )O S atelecl Mar. 11, 1941 "il NITED STATES PUMP AND PROCESS F SETTING THE PISTON THEREOF Ray D. Strelby, Canton, Ohio, assignor to The Tmken Roller Bearing Company, Canton, 0hio, a corporation of Ohio' Application March 26, i938, Serial No. 198,211

il Claims.

rlhis invention relates principally to fuel pumps for internal combustion engines of the Diesel type, particularly fuel injection pumps of the type shown in Olin Patent No. 2,079,660 of May ll, 1937, wherein a piston of constant stroke has an annular groove therein adapted, at a predetermined point in the delivery stroke of the piston,

to place the pressure chamber of the cylinder in communication with a by-pass port therein and thus relieve the pressure inV said chamber and terminate the fuel delivery, and said groove has a helical upper edge that is adjusted relative to said oy-pass port, to vary the quantity of fuel delivered and thus regulate the speed of the engine, by a piston turning mechanism comprising a driving sleeve having a pinion driven by a rack rod and a driven sleeve having a squared opening iitting a squared portion of said piston and an axially slidable connection with said driving sleeve comprising lntertting tangs on said sleeves. This type of pump requires a :ne initial angular setting of the piston in its cylinder in order to obtain the exact quantity of fuel delivery required for the properv operation of the engine.

The principal object of the invention is to obtain. an accurate initial angular setting of the piston in its cylinder without varying the position of the control or raclr rod for turning said piston. The invention consists in providing a set of one of the aforesaid sleeves, the tangs of the several sleeves of the set 'being in different angular positions with respect to the point of interlocking or-driving connection. ln the preferred form, a set of driven sleeves is provided, 'each sleeve of such set having its tangs offset with respect to the tangs of the other sleeves ol said set. ln the modification, a set of interchangeable driving sleeves is provided, each driving sleeve having its tangs offset a different distance from a selected tooth of its pinion. The invention also consists in the pump and the process of setting the piston thereof hereinafter described and claimed.

ln the accompanying drawings, which form part of this speci'lication and wherein lilre symhols refer to lilre parts wherever they occur,

Fig.. l is a central longitudinal section through a pump unit whose piston is initially set to deliver the normal or correct quantity of fuel,

Fig. 2 is a horizontal cross-section through the groove and loy-pass port oi the piston on the line i--il in. liig,I l,

Fig. 3 is a horizontal section on the line i-i in Fig. l,

Figs. Il, 5 and 6 are sections similar to Figs. l,

(ill. B-4i) 2 and 3, showing a pump unit whose initial piston setting provides an over normal fuel delivery,

Figs. 7, and 9 are views similar to Figs. 1, 2 and 3, showing a pump unit whose initial piston setting provides an under normal fuel delivery,

Figs. 10, 1l and 12 are plan views of three of the driven sleeves of the sets used in obtaining the desired initial angular setting of the piston,

Figs. 13, li and are views similar to Figs. 10, ll and 12 illustrating three sleeves of a modified form of set of driving sleeves used for 0btaining the desired initial angular adjustment of the piston; and

Fig. 16 is a view of a chart used in angularly setting the pump pistons.

In the accompanying drawings, my invention is illustrated in connection with a pump unit adapted for mounting in the bore of a pump housing (not shown).. Said pump unit comprises a cylinder or barrel l having a piston 2 reciprocating therein and a radial inlet port 3 on one side and a radial overilow or bypass port i on the opposite side. A valve block `5 rests upon the upper end of the cylinder and has a bore that leads from the pressure chamber t and is normally closed by means of a suitable spring loaded delivery valve l.

The piston l is mounted for both rotary and.

axial sliding movement in the cylinder l and is of the-general type having an annular groove t therein that communicates through a longitudinal peripheral groove i with the pressure space t above said piston and has an inclined or helical upper edge portion it, whereby said piston may be turned in said cylinder to vary the point in its delivery stroke at which the by-pass port t is placed in communication with said pressure space through said grooves. By this arrangement, delivery of the fuel through the spring loaded delivery valve l begins as soon as the piston on its way up covers the ports il and il and ends as soon as the helical upper edge it of `the annular groove l in said piston opens the overiiow port il andthus relieves the pressure in the space li above said piston. The usual tappet (not shown) cooperates with the lower end of the piston for im parting an upward or pressure stroke thereto; and the usual spring (not shown) is einn ployed for imparting the downward or suction stroke to said piston.

The mechanism for turning the piston i in the cylinder l to vary the amount of fuel supplied to the engine for different speeds and load conditions preferaloly comprises apinion li rigid with the upper end of a cylindrical sleeve li that is rotatably mounted on said cylinder and hasan axially slidable driving connection with a sleeve I3 that has a rigid connection with said piston below said cylinder. The driving connection between the driving land driven sleeves comprises downwardly extending diametrically opposed tongues or tangs I4 on the driving or regulating sleeve I2 that fit within upwardly extending diametrically opposed notches formed lby upwardly extending diametrically opposed tongues or tangs I5 on the driven or piston connecting sleeve I3, thereby permitting relative axial movement of the two sleeves, but preventing relative rotary movement thereof. The rigid connection between the driven sleeve I3 and the piston 2 comprises a' squared or fiat-sided portion I6 on said piston that snugly fits a similarly shaped opening II in the bottom or lower end of said driven sleeve. Any suitable means (not shown) may be provided for preventing relative axial movement of said piston and said driven sleeve and the driving sleeve and the cylinder.

The driving sleeve I2 is rotated by means of a control rod I8 that is mounted in the pump housing (not shown) for axial sliding movement transversely of the driving sleeve axis and has a series of rack teeth I9 that intermesh with the teeth of the pinion II on said sleeve. When the rod I8 isl shifted to bring the lowest part of the upper edge of the annular groove 8 of the piston in line with the by-pass port 4 of the cylinder, the maximum fuel delivery is obtained, and when said rod is shifted to bring the highest portion of said edge of said groove in line with said port the minimum fuel delivery is obtained.

While the hereinbefore described arrangement permits the quantity of the fuel to be varied during the operation of the pump, an initial permanent angular setting of the piston is necessary in order that the pump will operate at its rated capacity or predetermined standard over the whole range of its operation. According to the present invention, this fine initial angular setting of the piston is obtained with a plurality or set of driven sleeves I3 each having its square piston receiving opening offset circumferentially at slightly different amounts with relation to its tangs I5. This set may comprise any desired,

number of driven sleeves having their tangs in different angular positions with respect to their squared piston receiving openings, say in angular increments of one-half degree with one degree of angular difference making a difference of 1 cu. mm. in fuel delivery for each pressure stroke of said piston. With this arrangement, when it is desired to set the pump for the rated capacity, the driven sleeve which has been Selected as standard for a pump of said rated capacity is mounted on the piston and the pump unit tested to determine whether it delivers the correct quantity of fuel. If the test shows that the pump unit delivers more or less fuel than is desired, the unit is again tested with other sleeves of the set until a sleeve is found that will position the helical edge I0 of the groove lof the piston relative to the by-pass port so as to bring about the proper fuel delivery.

In the modification shown in Figs. 13, 14 and 15, the correct fuel delivery is obtained by means of a set of driving sleeves I2, having their tangs olTset circumferentially preferably in angular increments of one-half degree with respect to two adjacent punched marked teeth I Ia of the pinions I I thereon. In the use of this set of sleeves, the punched marked teeth IIa thereof are engaged with a double tooth space I9a provided therefor in the rack I9 of the control rod I8; and if, when the pump is tested, it delivers a quantity of fuel greater or less than the quantity desired, the pump is again tested with the different driving sleeves of the set until a sleeve is found that will position the helical edge I8 of the annular groove 8 of the piston relative to the by-pass port 4 so as to bring about the desired fuel delivery.

The sleeves are preferably numbered, one being standard and those numbered above the standard number being used to correct over delivery of fuel and those numbered below the standard number being used to correct under delivery of fuel. The chart shown in Fig. 16 may be used to indicate the particular sleeve required to obtain the correct fuel delivery. On this chart the fuel delivery requirements at various speeds at one-fourth, one-half and three-fourths throttle positions are indicated by the curved lines 20, 2I and 22, respectively. By'use of these Curves and the numbered sleeves the proper sleeve may be readily determined. For instance, when the pumpis' tested with the standard sleeve and found to deliver l0 cu. mm. at one-fourth throttle at 200 R. P. M. istead of a required delivery of say 16 cu. mm., another sleeve would be selected twelve numbers higher, thus bringing the fuel delivery up to standard requirements at all throttle positions and speeds.

The above described invention provides a very simple arrangement for accurately setting the piston of a pump of the kind described without varying the relative position of the rack rod and pinion and without changing thethrow or setting of said rod; and it also enables all of the pistons of a multicylinder pump to be set to deliver equal quantities of fuel.

What I claim is:

1. A pump comprising a cylinder having a bypass port therein, a piston in said cylinder having a groove with a helical edge adapted at a predetermined point in the pressure stroke of said piston to establish communication between said port and the pressure chamber of said cylinder, a driven sleeve fixed to said piston, a driving sleeve rotatable about the axis of said piston and having a pinion and an axial sliding driving connection with said driven sleeve, and an axially slidable control rod having a rack intermeshing with said pinion, one of said sleeves constituting -one of a set of sleeves adapted for interchangeable use with said pump, the circumferential relation of the points of connection between said one `sleeve of said set and the driving member therefor and the member driven thereby being different from the corresponding relation of such points of connection of any other sleeve of said set, whereby said one sleeve of said set is adapted to provide a selected setting of said helical edge of said groove relative to said by-pass port different from that of any other sleeve of said set.

2. A pump comprising a cylinder having a bypass port therein, a piston in said cylinder having a groove with a helical edge adapted at a predetermined point in the pressure stroke of said piston to establish communication between said port and the pressure chamber of said cylinder, a driven sleeve fixed to said piston, a driving sleeve rotatable about the axis of said piston and having a pinion and an axial sliding driving connection with said driven sleeve, and an axially slidable control rod having a rack intermeshing with said pinion, one of said sleeves constituting one of a set of sleeves adapted for interchangeinder, a driven sleeve able use with said pump, the circumferential relation of the points of connection between said one sleeve of said set and the driving member therefor and the member driven thereby being different from the corresponding relation of Such points of connection of any other sleeve of said set, whereby said one sleeveof said set is adapted to provide a. selected setting of said helical edge of said groove relative to saidby-pass port diierent from that of any other sleeve of said set without changing the endwise position or stroke of said control rod, said one sleeve of said set being adapted to bring about an angular setting of said piston that will effect a predetermined change in the quantity of fluid discharged by said pump different from that of any other sleeve of said set.

3. A pump comprising a cylinder, a piston in said cylinder having a ilatsided portion, said cyll inder having a by-pass port and said piston having a groove with a helical edge adapted at a predetermined point in the pressure stroke of said piston to establish communication between said port and the pressure chamber of said cyl- Iixed to said piston having circumferentially spaced tangs and a natsided axial opening adapted to snugly receive the flatsided portion of said piston, a drivingsleeve rotatable about the axis of said piston and having a i0 pinion and circumferentially spaced tangs that nt between the tangs of said driven sleeve and y form an axial sliding driving connection therewith, and a longitudinally slidable control rod having a rack intermeshingwlth the pinion of said driving sleeve, said driven sleeve constituting one of a set of driven sleeves adapted to be interchangeably received by the flatsided portion of said piston and by the tangs of said driving sleeve, the circumferential relation of the tangs to the flatsided opening of said one sleeve of said set being different from the corresponding relation of the tangs and the flatsided opening of any other sleeve of said set, whereby said. one

sleeve of said set is adapted to effect an angular setting of said helical' edge of said groove different from that of any other sleeve of said set without changing the setting or stroke of said control rod.

fi. A pump comprising a cylinder, a piston in said cylinder, said cylinder having a by-pass port and said piston having a groove with a helical edge, adapted at a predetermined point in the pressure stroke of said piston to establish communication between said port and the pressure r .s chamber of said cylinder, a driven sleeve xed to said piston and having circumferentially spaced tangs, a driving sleeve rotatable about the axis of said piston and having a pinion and circumferentially spaced tangs that fit between the tangs of said driven sleeve to form an axial sliding driving connection therewith, and a con- -trol rod having a rack intermeshing with the pinion of said driving yleeve, saiddriving sleeve constituting one of a set of such sleeves adapted to be interchangeably engaged with said rack and said driven sleeve, said one sleeve of said set having its tangs offset circumferentially a, different distance from a selected tooth of its pinion different from that of any other sleeve of said Set. whereby said one sleeve of said set is adapted for interchangeable use with said driven sleeve and to provide an angular setting of said helical edge of said groove different from that of any other sleeve of said set without changing the position or stroke of said control rod.

5. A fuel injection pump comprising acylinder, a piston mounted in said cylinder, and means providing for relative rotary adjustment of saidi cylinder and piston to vary the quantity of fuel injected, said means including a driven member fixed to one of said piston and cylinder, said member constituting one of a set of such members adapted-for interchangeable use with said pump, the circumferential relation of the drive receiving and drive delivering .portions of said one member of said set being deferent from the circumferential relation of the corresponding portions of every other member of said set, whereby said one member of said set is adapted to bring about a permanent initial relative rotary setting of said piston and cylinder different from that of any other member of said set.

6. A fuel injection pump comprising a cylinder, a piston working in said cylinder and rotatably adjustable therein to vary the quantity of fuel injected, and means providing for such rotary adjustment of said piston including a driven sleeve fixed to said piston and a driving sleeve having a driving connection with said driven sleeve, one of said sleeves constituting one of a setA of sleeves adapted for interchangeable use with said pump, the circumferential relation of the drive receiving and drive delivering portions of said one sleeve of the circumferential relation of the corresponding `portions of every other sleeve of said set, whereby said one sleeve of said set is adapted to bring about a permanent initial rotary setting of said piston in` said cylinder different from that of any other sleeve of said said set.

7. A fuel injection pump comprising a cylinder, a piston working in said cylinder and turning said piston in said cylinder to vary the quantity of fuel injected, said means including a driven sleeve fixed to said piston and having crcumferentially spaced tangs and a driving sleeve having circumferentially spaced tangs that fit between the tangs of said driven sleeve and form a driving connection thereby, one of said sleeves constituting one of a set of such sleeves adapted for interchangeable use with said piston, the circumferential relation of the tangs and the piston engaging portions of said one sleeve of said set being different from the circumferential relation of the corresponding l portions of every other sleeve of said set, whereby said one sleeve of said set is adapted to bring about an initial rotary setting of said piston in said cylinder different from that of any other sleeve of said set.

8; A fuel injection pump comprising a cylinder,

a piston Working in said cylinder and rotatably adjustable therein to vary the quantity of fuel injected, and means providing for such rotary adjustment of said pistonincluding a pinion having an axial sliding driving connection with said piston and a member intermeshing with said pinion for turning the same, said pinion constituting one of a set of pinions adapted for interchangeable use with said pump, the circumsaid set being different from means for ferential relation of a selected tooth and drive vdelivering portions of said one pinion of said set being different from the circumferential relation of the corresponding portions of every other pinion of said set, whereby said one pinion of said set is adapted to bring about a permanent initial rotary setting of said piston different from that of any other pinion of said set. i

RAY D. STREBY. 

